HR: 0800h
AN: V11C-0751    [Abstracts]
TI: The Radon monitoring network at Stromboli Volcano: tracking precursors and earthquake- volcano interactions
AU: * Laiolo, M
EM: marco.laiolo@unito.it
AF: DSMP, University of Torino, Via Valperga Caluso 35, Torino, PMT 10125, Italy
AU: Cigolini, C
EM: corrado.cigolini@unito.it
AF: DSMP, University of Torino, Via Valperga Caluso 35, Torino, PMT 10125, Italy
AU: Coppola, D
EM: diego.coppola@unito.it
AF: DSMP, University of Torino, Via Valperga Caluso 35, Torino, PMT 10125, Italy
AB: We investigated radon soil degassing at Stromboli volcano since May 2002. We used E-PERM electretes (1-4 days exposure) and Track-Etch detectors (20-40 days exposure) to evaluate background levels and anomalous values in radon emissions for the operating radon network consisting of 25 stations. These values were used to construct keys maps that identify radon anomalies due to changes in volcanic activity and/or the occurrence of major seismic events. Higher emissions are concentrated at the summit and along the NE sector of the island (controlled by faults trending N40 and N60). Automated measurements started May 2005 at two distinct summit sites. Data processing outline a general correlation between atmospheric pressure and radon degassing. Moreover, comparison of our data with those collected by INGV on carbon dioxide shows a very strong correlation, thus further supporting the idea that CO2 is an active "radon carrier". Measurements of the radon progeny (218Po and 214Po) give us a clue to discriminate between the residing gas in the porous medium and the "new coming" 222Rn parent. Under isotopic equilibrium conditions the ratio 222Rn/214Po should be equal to unity. Conversely under dynamic conditions, an increase in radon fluxing (from below) will result in an increase of 222Rn with respect to 214Po. Activity versus time graphs show that major explosions are preceded by the crossing over of 222Rn onto the 214Po curve. We finally analyzed the link between radon emissions, volcanic tremor and number of VLP events. The overall data show a general time-correlation among these parameters, and further indicate that radon is a key parameter in volcano suirvellance
DE: 8419 Volcano monitoring (7280)
DE: 8428 Explosive volcanism
DE: 8430 Volcanic gases
DE: 8494 Instruments and techniques
DE: 9335 Europe
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting